Modular sensor array for bulk material detection

ABSTRACT

A combine having a feeder housing for receiving harvested crop, a separating system for threshing the harvested crop to separate grain from residue, a grain tank for storing the separated grain, a grain tank level sensor for detecting a level of grain in the grain tank, and a controller that controls the combine. The controller is configured to receive the level of grain from the grain tank level sensors, determine a volume of a grain base from the level of the grain, determine a volume of a grain heap above the grain base, determine a total volume by combining the volume of the grain base with the volume of the grain heap.

FIELD

The disclosure relates to grain tank measurement system and method forestimating grain volume in a grain tank of a combine.

BACKGROUND

Harvesters (e.g. combines) are used to harvest crops. Operationsperformed by conventional combines include chopping the crop andcollecting grain in a grain tank. These conventional combines, however,utilize grain quantity measurement devices and methods that aresusceptible to grain measurement inaccuracies and grain spillage.

SUMMARY

An embodiment includes a combine having a feeder housing for receivingharvested crop, a separating system for threshing the harvested crop toseparate grain from residue, a grain tank for storing the separatedgrain, a grain tank level sensor for detecting a level of grain in thegrain tank, and a controller that controls the combine. The controlleris configured to receive the level of grain from the grain tank levelsensor, determine a volume of a grain base from the level of the grain,determine a volume of a grain heap above the grain base, and determine atotal volume by combining the volume of the grain base with the volumeof the grain heap.

An embodiment includes a method for controlling a combine having achassis, a feeder housing for receiving harvested crop, a separatingsystem for threshing the harvested crop to separate grain from residue,a grain tank for storing the separated grain, a grain tank level sensorfor detecting a level of grain in the grain tank, and a controller thatcontrols the combine. The method includes the steps of receiving, by thecontroller, the level of grain from the grain tank level sensor,determining, by the controller, a volume of a grain base from the levelof the grain, determining, by the controller, a volume of a grain heapabove the grain base, determining, by the controller, a total volume bycombining the volume of the grain base with the volume of the grainheap.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a side view of a combine, according to an embodiment of thedisclosure.

FIG. 1B is a close-up view of the grain tank level sensors on a combine,according to an embodiment of the disclosure.

FIG. 2A is a perspective view of the grain tank of the combine,according to an embodiment of the disclosure.

FIG. 2B is a top view of the grain tank of the combine, according to anembodiment of the disclosure.

FIG. 3A shows multiple views of the grain tank level sensors, accordingto an embodiment of the disclosure.

FIG. 3B is a perspective view of the sensor array, according to anembodiment of the disclosure.

FIG. 3C is a schematic view of the wiring in the sensor array, accordingto an embodiment of the disclosure.

FIG. 4 is a view of the communication between the combine control systemand an external network, according to an embodiment of the disclosure.

FIG. 5A is a view of the grain base and the grain heap, according to anembodiment of the disclosure.

FIG. 5B is a view of a sphere for estimating the grain heap volume,according to an embodiment of the disclosure.

FIG. 5C is a view of a cone for estimating the grain heap volume,according to an embodiment of the disclosure.

FIG. 5D is a 3-dimensional view of the grain base detected by triggeredsensors, according to an embodiment of the disclosure.

FIG. 5E is a 3-dimensional view of a best fit surface drawn through thetriggered sensors, according to an embodiment of the disclosure.

FIG. 5F is a 3-dimensional view of a section of best fit surfaceenclosed by vertical projection of base vertices, according to anembodiment of the disclosure.

FIG. 5G is a 3-dimensional view of an estimated grain heap volume basedon a plane of best fit, according to an embodiment of the disclosure.

FIG. 6A is a flowchart for estimating the grain tank volume and grainheap volume, according to an embodiment of the disclosure.

FIG. 6B is a flowchart for controlling the combine based on theestimated the grain tank volume and grain heap volume, according to anembodiment of the disclosure.

DETAILED DESCRIPTION

Aspects of the disclosure provide methods and systems for operatoradjustable tank level measurement for implementation in a harvestercombine.

The terms “grain,” “straw,” and “tailings” are used principallythroughout this specification for convenience but it is to be understoodthat these terms are not intended to be limiting. Thus “grain” refers tothat part of the crop material which is threshed and separated from thediscardable part of the crop material, which is referred to as non-graincrop material, material other than grain (MOG).

Referring now to the drawings, and more particularly to FIG. 1A, thereis shown one embodiment of an agricultural harvester in the form of acombine 10, which generally includes a chassis 12, ground engagingwheels 14 and 16, a header 18, a feeder housing 20, an operator cab 22,a threshing and separating system 24, a cleaning system 26, a grain tank28, and an unloading auger 30.

Front wheels 14 are larger flotation type wheels, and rear wheels 16 aresmaller steerable wheels. Motive force is selectively applied to frontwheels 14 through a power plant in the form of a diesel engine 32 and atransmission (not shown). Although combine 10 is shown as includingwheels, is also to be understood that combine 10 may include tracks,such as full tracks or half-tracks.

Header 18 is mounted to the front of combine 10 and includes a cutterbar 34 for severing crops from a field during forward motion of combine10. A rotatable reel 36 feeds the crop into header 18, and a doubleauger 38 feeds the severed crop laterally inwardly from each side towardfeeder housing 20. Feeder housing 20 conveys the cut crop to threshingand separating system 24, and is selectively vertically movable usingappropriate actuators, such as hydraulic cylinders (not shown).

Threshing and separating system 24 is of the axial-flow type, andgenerally includes a rotor 40 at least partially enclosed by androtatable within a corresponding perforated concave 42. The cut cropsare threshed and separated by the rotation of rotor 40 within concave42, and larger elements, such as stalks, leaves and the like aredischarged from the rear of combine 10. Smaller elements of cropmaterial including grain and non-grain crop material, includingparticles lighter than grain, such as chaff, dust and straw, aredischarged through perforations of concave 42.

Grain separated by the threshing and separating assembly 24 falls onto agrain pan 44 and is conveyed toward cleaning system 26. Cleaning system26 may include an optional pre-cleaning sieve 46, an upper sieve 48(also known as a chaffer sieve), a lower sieve 50 (also known as acleaning sieve), and a cleaning fan 52. Grain on sieves 46, 48 and 50 issubjected to a cleaning action by fan 52 which provides an airflowthrough the sieves to remove chaff and other impurities such as dustfrom the grain by making this material airborne for discharge from strawhood 54 of combine 10. Grain pan 44 and pre-cleaning sieve 46 oscillatein a fore-to-aft manner to transport the grain and finer non-grain cropmaterial to the upper surface of upper sieve 48. Upper sieve 48 andlower sieve 50 are vertically arranged relative to each other, andlikewise oscillate in a fore-to-aft manner to spread the grain acrosssieves 48, 50, while permitting the passage of cleaned grain by gravitythrough the openings of sieves 48, 50.

Clean grain falls to a clean grain auger 56 positioned crosswise belowand in front of lower sieve 50. Clean grain auger 56 receives cleangrain from each sieve 48, 50 and from bottom pan 62 of cleaning system26. Clean grain auger 56 conveys the clean grain laterally to agenerally vertically arranged grain elevator 60 for transport to graintank 28.

Tailings from cleaning system 26 fall to a tailings auger trough 64. Thetailings are transported via tailings auger 64 and return auger 66 tothe upstream end of cleaning system 26 for repeated cleaning action. Apair of grain tank augers 68 at the bottom of grain tank 28 convey theclean grain laterally within grain tank 28 to unloading auger 30 fordischarge from combine 10.

The non-grain crop material proceeds through a residue handling system70. Residue handling system 70 includes a chopper, counter knives, awindrow door and a residue spreader. When combine 10 operating in thechopping and spreading mode, the chopper is set to a relatively highspeed (e.g. 3,000 RPM), the counter knives may be engaged, the windrowdoor is closed and the residue spreader is running (e.g. rotating). Thiscauses the non-grain crop material to be chopped in to pieces ofapproximately 6 inches or less and spread on the ground in a fairlyuniform manner. In contrast, when combine 10 is operating in the windrowmode, the chopper is at a relatively low speed (e.g. 800 RPM), thecounter knives are disengaged and the windrow door is open. The residuespreader may continue operation to spread only the chaff, with the cropmaterial passing through the passageway created by the open windrowdoor.

A controller (not shown in FIG. 1A) measures the collected grain todetermine if the grain tank 28 is full. The controller measures thegrain with the aid of grain level sensors located within grain tank 28.In one example, shown in FIG. 1B, a first grain tank level sensor array100 and a second grain tank level sensor array 102 are located along theinterior walls of grain tank 28. A third grain tank level sensor array101 and a fourth grain tank level sensor array 103 (e.g. center arrays)are located in the center of grain tank 28 and extend from the base ofthe grain tank away from the tank walls towards the center of the graintank. Grain tank level sensor arrays 100, 101, 102 and 103 may includean array of acoustic sensors, pressure sensors, optical sensors, and/orthe like that detect the presence of grain in the tank in a local regionsurrounding the sensor.

Grain tank level sensor arrays 100-103 in FIG. 1B extend from a bottomportion of the grain tank to a top portion of the tank. Grain tank levelsensor arrays 100-103 may include optical sensors such as infrared (IR)sensors that transmit an IR beam of light. If grain fills the tank andcovers an IR sensor, the IR light reflects back to the IR receiver,thereby triggering the sensor. A controller receives a trigger signalfrom the sensor and determines the level of grain in the tank based onthe known location of the sensor within the tank. For example, whengrain pile 104 is present in the tank, the 1^(st)-9^(th) sensors inarrays 100 and 102 trigger, and the 1^(st)-8^(th) sensors in arrays 101and 103 trigger. These triggered sensors correspond to a predeterminedlevel (e.g. 75%) of grain within the tank. In this example, when thegrain triggers the sensors, the controller determines that the grainheap surface is located at the location of the 9^(th) sensor.Notifications such as a display of the tank level, tank volume, or atrigger of an alarm are output to the operator.

The shape of the grain pile within the tank depends on various factorsincluding the slope of the ground that the combine is traveling on.Having multiple arrays of sensors at multiple locations within the tankprovides a system that is able to more accurately detect grain levelwhen the grain pile is not uniform. For example, as shown in FIG. 1B, onlevel ground, the detected levels between arrays are generally similar(e.g. sensors 100 and 102 both show 75% full) due to a uniform grainpile in the tank. However, when the combine is harvesting on a slope ora hill, and leaning forward, backward, to the left, or to the right, thelevels detected by sensor arrays 100 and 102 may not coincide due to theslope of a non-uniform grain pile in the tank (e.g. if the combine isharvesting downhill, sensors 100 may detect 75% and sensors 102 maydetect only 50%). This discrepancy is important to detect, because theside of the tank with the highest grain level is more likely to overflowand spill out of the top of the grain tank. Such spillage results inlost revenue.

In order to more accurately measure grain tank level, and avoidspillage, the combine includes multiple arrays (e.g. 3 or more) ofsensors at various locations within the grain tank (e.g. one centerarray in the middle of the tank and two side arrays along the tankwall). FIG. 2A shows a 3-dimensional view of an example of such a graintank configuration. Specifically, the grain tank in this example has a3-dimensional trapezoid-like shape extending from base 200 to top rim202. The grain tank includes four side arrays of level sensors 204, 206,208 and 210 positioned in the corners of the tank separated by an arrayspacing and extending along an array length from base 200 to top rim202. These sensor arrays are similar to the sensor arrays 100 and 102shown in FIG. 1B. The grain tank also includes two center arrays oflevel sensors 209 and 211 positioned extending along an array lengthfrom base 200 at an angle towards the center of top rim 202. Thesesensor arrays are similar to the sensor arrays 101 and 103 shown in FIG.1B.

The four sensor arrays in FIG. 2A provide the ability to detect sixgrain level points at six different locations within the tank. In thisexample, these arrays each have 12 sensors, which provide each arraywith a resolution of 12 detectable grain levels. In general, theaccuracy of the system increases as the number of arrays and number ofsensors within each array are increased. Thus, the number of arrays, thenumber of sensors within each array, and the locations of the arrayswithin the tank are configurable to achieve the desired accuracy.

For example, FIG. 2B shows a top view of tank 212 (i.e., looking down onthe top of the tank) that includes 12 side sensor arrays 214 positionedfrom each other by a set array spacing around the inner wall of the tankand one center sensor array 215 positioned in the center of the tank.This configuration provides 13 data points of grain tank levels aroundthe entire perimeter and the center of the tank. Assuming each arrayincludes 10 sensors, each array would be able to detect the tank filllevel at 10 discrete levels. The spacing of the array may beequidistant, or may follow other spacing patterns. In addition, thesensor arrays can extend along a partial height of the grain tank, andmay not necessarily be vertical (i.e., they could be diagonal) or maynot be directly in the center of the tank. In some examples, the arraysmay be curved (e.g. curved to follow the tank geometry), and segmented(e.g. positioned in portions of the tank). In general, anymathematically describable array configuration can be used to detect thegrain.

FIG. 3A shows multiple views of optical IR grain tank sensors usedwithin the arrays. Each sensor includes a housing 304 (e.g., plastic),an electrical circuit 308 for driving the sensor components andcommunicating with the controller, and a channel that allows a wirebundle 306 to pass through. Views 302A, 302B and 302C show variousperspective views of the same sensor, while view 302D shows a side viewof the sensor. An isolated view of electronic circuit 308 is also shown.In one example, electronic circuit 308 may include an IR transmitter, anIR receiver, and a driver circuit that drives the IR transmitter as wellas transmit/receive information to/from a controller (not shown). Inthis example, the sensors within the array may also be housed in acube-like sleeve 310 made from transparent material (e.g., clearplastic) which aligns the sensors in a package that is easily mountablewithin the grain tank, as well as protects the sensors from damage dueto the grain and other external factors. In other examples, other typesof sensors may be used in place of or in combination with the IRsensors. These other sensors include but are not limited to acousticsensors, laser sensors, radio frequency sensors and pressure sensors.

An example of the sensor array within cube-like sleeve 310 is shown inFIG. 3B. In this example, the sensor array includes 5 sensors 312 spacedequidistant throughout the array length of sleeve 310. Sensors 312electrically connect to the controller via wire bundle 314 that runswithin cube-like sleeve 310. Although only 5 sensors are shown, it isnoted that more than 5 sensors may be utilized. It is also noted thatthe sensors could be spaced apart in at different sensor spacingintervals that do not have to be equidistant. In addition, although notshown, the end of the wire bundle shown on the left of the figureconnects to the combine controller.

The electrical connections between the sensors and the combinecontroller are shown in the schematic diagram of FIG. 3C. Only twosensors 316 and 318 are shown for the sake of clarity. However, itshould be noted that the other sensors in the array would be connectedin a similar manner.

As shown in FIG. 3C, the wire bundle includes various wires whichinclude, but are not limited to a ground wire GND, a power wire PWR, anddata wires 5-1 to 5-8. In this example, there are 8 data wires toaccommodate 8 sensors in the array. In this example, all of the sensors,including sensors 316 and 318 shown connect to the GND and the PWR wiresin the wire bundle. These connections provide the sensors with theelectrical power required to drive the components in the sensor circuit.Although each sensor shares the same GND and PWR wires, each sensor hasa unique data wire. In this example, sensor 316 is the eighth sensor inthe array and therefore connects to data wire 5-8. Likewise, sensor 318is the seventh sensor in the array and therefore connects to data wire5-7. These data wires allow trigger signals to be transmitted from thesensors to the controller (not shown) which is also connected to datawires 5-1 to 5-8. In an alternative example, all of the sensors couldshare a common data wire configured as a data bus with scheduledtransmissions.

During operation, the GND and PWR wires power all of the sensorsincluding sensors 316 and 318 shown. The electric circuit uses thispower to emit an IR signal. When no grain is present, the IR receiverdoes not receive a reflection, and therefore the signal on data wires5-1 to 5-8 remains at a predetermined logic state (e.g. logic 0).However, when grain is present at sensor 316, the IR receiver doesreceive a reflection (i.e., the grain reflects the IR beam), andtherefore the signal on data wire 5-8 changes its logic state (e.g.logic 1). The controller is therefore able to determine that the grainis at the lowest level in the grain tank. As the grain level rises, thegrain triggers more sensors to output a logic 1. The number of logic 1's(i.e., triggered sensors) received by the controller indicates the grainlevel. For example, if 4 out of 8 sensors transmit a logic 1, then thecontroller determines that the grain tank is half full assuming thesensors are positioned at discrete volume levels within the tank.

FIG. 4 shows an example of a system 400 for controlling the combine. Thesystem 400 includes an interconnection between a control system 410 ofcombine 10, a remote PC 406 and a remote server 402 through network 404(e.g. Internet). It should be noted that combine 10 does not have to beconnected to other devices through a network. The controller of combine10 can be a standalone system that receives operating instructions (e.g.tank level instructions such as alert levels) through a user interface,through a removable memory device (e.g. Flash Drive) or from a server402 via transceiver 417 (e.g. Wi-Fi, Bluetooth, Cellular, etc.).

Prior to operating combine 10, an operator may designate the tank levelalerts and other tank level related instructions. In one example, theoperator uses interface 411 of the combine control system or PC 406located at a remote location. Interface 411 and PC 406 allow theoperator to view locally stored parameters from memory device 415 and/ordownload parameters from server 402 through network 404. The operatormay select (via Interface 411 or PC 406) appropriate tank level relatedinstructions based on various factors including, among others, the typeof crop to be harvested by the combine, and the terrain. Once the tanklevel related instructions are selected, the operator can beginharvesting. Combine controller 412 then controls actuators 414 (e.g.thresher, chopper, etc.) based on the instructions. For example, sensors416 (e.g. tank level sensor) may be used during harvesting to moreaccurately determine the grain level to avoid spillage. GPS receiver 413produces information to track harvesting and monitor terrain.

Although the grain tank level sensors detect the grain pile at multiplelocations within the tank, the grain pile includes a section of grainabove the grain level that is undetected by the sensors. This sectionwill now be described.

FIG. 5A shows a simplified view of a grain pile. As the grain elevatorpours the grain into tank 501 along path 505, two distinct volumes form.As shown, these two basic volumes include a grain base 502 and a grainheap 504. Grain base 502 is the volume of grain that forms the bottomportion of the grain pile. Grain base 502 touches the sidewalls (andtherefore the triggered sensors 503A and 503C) of the grain tank asshown in FIG. 5A. Thus, the grain level is based on the detection ofgrain base 502. In this example, the grain level based solely on thegrain base 502 is 50% of the grain tank volume.

However, it is clear from FIG. 5A, that the grain pile is much higherthan indicated by the level of the grain base 502. A portion of the pileknown as grain heap 504 sits on top of the grain base and is much closerto the top of the grain tank 501 and more prone to spillage. The grainheap forms due to the manner in which the elevator pours the grain intothe grain tank from above, and the friction between the grains. As canbe seen in FIG. 5A, the grain heap 504 is not touching the sides of thegrain tank, and is therefore only detected by triggered center sensor503B.

In order to more accurately determine the grain tank level, the volumeof the grain heap 504 should be determined. There are multiple methodsfor determining the volume of the grain heap 504. One such method is toestimate the volume of the grain heap 504 as a known geometric shape(e.g., sphere, cone, etc.) which is a mathematically describable shape.

In one example, the volume of the grain heap may be estimated based on asphere 506 shown in FIG. 5B. The sphere 506 has a bottom portion 506Aand a top portion 506B. The sphere 506 also includes a radius R thatextends from a center-point. The top portion 506B is a cross-section ofthe sphere that has a height ‘h’ that is fraction of radius R andlocated at an angle of repose

. The grain heap 504 may be estimated by choosing the height ‘h’ and aradius ‘R’ of sphere section 506B that best represents the grain heap504 from FIG. 5A based on various factors including the grain tank leveldetected by the sensors, the geometry of the grain tank, etc. Forexample, radius ‘R’ can be determined based on the horizontal distancebetween triggered side sensors 503A and 503C, whereas the height ‘h’ canbe determined based on the vertical distance between the side sensors tothe triggered center sensor 503B.

In an alternative example, the volume of the grain heap 504 may beestimated based on a cone 508 as shown in FIG. 5C. The cone in FIG. 5Chas a radius ‘r’ that extends from a center-point, and a height ‘h’ thatextends from the base 508A to the peak 508B. Similar to the sphereexample, the grain heap 504 may be estimated by choosing the height ‘h’and a radius ‘r’ of the cone that best represents the grain heap 504based on various factors including the grain tank level detected by thesensors, the geometry of the grain tank, etc. For example, radius ‘r’can be determined based on the horizontal distance between triggeredside sensors 503A and 503C, whereas the height ‘h’ can be determinedbased on the vertical distance between the side sensors to the triggeredcenter sensor 503B.

Known geometrical shapes are not necessary for estimating the volume ofthe grain heap 504. For example, another method for estimating thevolume of the grain heap could be based on a complex 3-dimensional shapefrom the grain tank levels. An example of such a complex mathematicallydescribable shape is shown in FIGS. 5D-5G. In this example, thecontroller may be configured to determine a volume of the grain heap 504by estimating a plane of best fit representing the top of the grain base(e.g. the top surface of grain base 502). This plane of best fit may bebased on the detected levels within the grain tank.

For example, the system may include sensor arrays positioned in thecenter region of the grain tank, and sensor arrays positioned atlocations than near the walls of the tank. The information from the sidewall sensor arrays and the center sensor arrays provides data to draw abest-fit surface through triggered sensors from the wall arrays andcenter arrays. This may be accomplished by way of a surface-fittingfunction. In this way, a non-geometric shaped grain heap surface can bedescribed mathematically by a set of point coordinates that are greaterin number than the number of sensor arrays, that when connected withtriangular facets, create an irregular surface that closely matches thetrue grain heap surface. Since the surface described by the fittingfunction may not have clear boundaries, a polygon created by connectingwall array sensors that lie on the base plane (referred to as the grainheap base) can be projected vertically to create an outside boundaryenclosing the portion of the best-fit surface that represents the grainheap. The volume enclosed between the remaining enclosed best-fitsurface section and the base plane represents that heap volume.

This process is illustrated in FIGS. 5D-5G. For example, FIG. 5D shows a3-dimensional view of the grain base detected by triggered sensors(black dots) in the side arrays (8 dashed lines) and center arrays (4dashed lines). FIG. 5E shows a 3-dimensional view of a best fit surfacedrawn through the triggered sensors and superimposed over the grain basefrom FIG. 5D. FIG. 5F shows a 3-dimensional view of a section of bestfit surface enclosed by vertical projection of base vertices extendingfrom the bottom of the grain base to the top surface of the heap. FIG.5G shows a 3-dimensional view of an estimated grain heap volume based onthe plane of best fit in FIG. 5F.

Regardless of the method used to determine the volume of the undetectedgrain heap 504, the controller is able to determine the total volume ofgrain in the grain tank by combining the volume of the grain heap withthe volume of the grain base. This may be used to keep track of theamount of grain in the tank, and determine if an alarm should be soundedto avoid spillage.

FIG. 6A is a flowchart 600 for estimating the grain tank level and thegrain heap volume. In step 601, the controller receives signals from thesensor array indicating grain levels at 3 or more locations (e.g. twoside locations and one center location) in the grain tank. Thecontroller uses this information to determine the volume of the grainbase. In step 602, the controller determines if the estimate of thegrain heap is to be performed by geometric approximation or not. Ifgeometric approximation is to be used, the controller chooses ageometric shape to represent the grain heap in step 603, estimates thevolume of the grain heap in step 604 by using a surface fitting methodto mathematically approximate the grain heap surface as the selectedgeometric shape, and combines to volume of the grain base and grain heapto determine the total grain volume in the tank. If geometricapproximation is not used, the controller chooses a surface fittingfunction in step 606, sets surface fitting function parameters in step607, estimates the volume of the grain heap in step 604 by projectingvertices of a polygon from the surface of the base, and combines thevolume of the grain base and grain heap to determine the total volume inthe tank.

Once the total volume of the grain tank is determined, the controllerand/or operator controls the combine accordingly. For example, FIG. 6Bis a flowchart 650 for controlling the combine based on the estimatedvolumes. The controller determines the grain tank level using sensors instep 651, estimates grain base volume and grain heap volume in step 652,estimates total volume (e.g. number of bushels) and filling rate (e.g. %full) in step 653, and displays total volume and/or filling rate in step654. The controller then compares the volume and/or filling rate torespective thresholds in step 655. If either value is greater than thethreshold, then the controller issues an alert to the driver in step656. The alert lets the driver know that a specific volume has beenreached, or that spillage may occur.

The controller may output various metrics to represent the grain volumeand/or filling rate. These metrics may include the number of bushels ofgrain in the tank, the percentage of grain tank that is full, etc. Thethresholds may be set based on volume and/or based on the percentage ofgrain tank that is full. In addition, the controller may display thesemetrics as numbers on the combine display screen, or as a graphicsimilar to FIG. 5A that shows the operator the state of the grain tank.

The steps of estimating the grain tank level in FIGS. 6A and 6B areperformed by control system 410 including controller 412 upon loadingand executing software code or instructions which are tangibly stored ona tangible computer readable medium 415, such as on a magnetic medium,e.g., a computer hard drive, an optical medium, e.g., an optical disc,solid-state memory, e.g., flash memory, or other storage media known inthe art. Thus, any of the functionality performed by the controller 412described herein, such as the steps shown in FIGS. 6A and 6B, areimplemented in software code or instructions which are tangibly storedon a tangible computer readable medium. Upon loading and executing suchsoftware code or instructions by the controller 412, the controller 412may perform any of the functionality of the controller 412 describedherein, including the steps shown in FIGS. 6A and 6B described herein.

The term “software code” or “code” used herein refers to anyinstructions or set of instructions that influence the operation of acomputer or controller 412. They may exist in a computer-executableform, such as machine code, which is the set of instructions and datadirectly executed by a computer's central processing unit or by acontroller, a human-understandable form, such as source code, which maybe compiled in order to be executed by a computer's central processingunit or by a controller, or an intermediate form, such as object code,which is produced by a compiler. As used herein, the term “softwarecode” or “code” also includes any human-understandable computerinstructions or set of instructions, e.g., a script, that may beexecuted on the fly with the aid of an interpreter executed by acomputer's central processing unit or by a controller.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather various modifications may be madein the details within the scope and range of equivalence of the claimsand without departing from the invention.

The invention claimed is:
 1. A combine comprising: a feeder housing forreceiving harvested crop; a separating system for threshing theharvested crop to separate grain from residue; a grain tank for storingthe separated grain; a grain tank level sensor for detecting a level ofgrain in the grain tank; and a controller that controls the combine, thecontroller configured to: receive the level of grain from the grain tanklevel sensor, determine a volume of a grain base from the level of thegrain, determine a volume of a grain heap above the grain base, anddetermine a total volume by combining the volume of the grain base withthe volume of the grain heap.
 2. The combine of claim 1, wherein thecontroller is further configured to determine the volume of the grainheap based on a mathematically describable shape.
 3. The combine ofclaim 1, wherein the controller is further configured to determine thevolume of a grain base below the grain heap based on a geometry of thegrain tank.
 4. The combine of claim 3, wherein the controller is furtherconfigured to determine a volume of the grain heap by estimating a planeof best fit representing the grain base, and using a plurality of graintank level sensors, a best-fit surface is determined with a boundaryidentified as a vertical projection of base vertices, a volume enclosedbetween the section of best-fit surface and the base represents thevolume of the grain heap.
 5. The combine of claim 4, wherein thecontroller is further configured to determine the total volume of grainin the grain tank by superimposing the volume of the grain heap on topof the volume of the grain base.
 6. The combine of claim 5, wherein thecontroller is further configured to determine a filling degree of thegrain tank based on the grain tank level sensor data, the filling degreeindicates how the grain tank is being filled by the grain.
 7. Thecombine of claim 6, wherein the controller is further configured tocompare the filling degree to a filling degree threshold, and issue awarning when the filling degree exceeds the filling degree threshold, orwherein the controller is further configured to compare the total volumeof the grain to a volume threshold, and issue a warning when the totalvolume of the grain exceeds the volume threshold.
 8. The combine ofclaim 1, wherein the grain tank level sensor includes at least threegrain tank level sensors positioned around the grain tank.
 9. Thecombine of claim 8, wherein the grain tank level sensors each include anarray of sensors configured to detect grain in a region local to thearray, each extending from a bottom portion of the grain tank to anupper portion of the grain tank.
 10. The combine of claim 9, whereinsensors in each array include at least one of optical sensors orpressure sensors.
 11. A method for controlling a combine including achassis, a feeder housing for receiving harvested crop, a separatingsystem for threshing the harvested crop to separate grain from residue,a grain tank for storing the separated grain, a grain tank level sensorfor detecting a level of grain in the grain tank, and a controller thatcontrols the combine, the method comprising: receiving, by thecontroller, the level of grain from the grain tank level sensor,determining, by the controller, a volume of a grain base from the levelof the grain, determining, by the controller, a volume of a grain heapabove the grain base, and determining, by the controller, a total volumeby combining the volume of the grain base with the volume of the grainheap.
 12. The method of claim 11, further comprising: determining, bythe controller, the volume of the grain heap based on a known geometricshape.
 13. The method of claim 11, further comprising: determining, bythe controller, a volume of a grain base below the grain heap.
 14. Themethod of claim 13, further comprising: determining, by the controller,a volume of the grain heap by estimating a plane of best fitrepresenting a base of the grain heap, and, using a plurality of graintank level sensors, a best-fit surface is determined with a boundaryidentified as a vertical projection of base vertices, the volumeenclosed between a section of best-fit surface and the base representsthe volume of the grain heap.
 15. The method of claim 14, furthercomprising: determining, by the controller, a total volume of grain inthe grain tank by superimposing the volume of the grain heap on top ofthe volume of the grain base.
 16. The method of claim 15, furthercomprising: determining, by the controller, a filling degree of thegrain tank based on the grain tank level sensor data, the filling degreeindicates how the grain tank is being filled by the grain.
 17. Themethod of claim 16, further comprising: comparing, by the controller,the filling degree to a filling degree threshold, and issue a warningwhen the filling degree exceeds the filling degree threshold, orcomparing, by the controller, the total volume of the grain to a volumethreshold, and issue a warning when the total volume of the grainexceeds the volume threshold.
 18. The method of claim 11, furthercomprising: wherein the grain tank level sensor includes at least threegrain tank level sensors positioned around the grain tank equidistantfrom one another for detecting the level of grain at least threepositions in the grain tank.
 19. The method of claim 18, wherein thegrain tank level sensors each include an array of sensors configured todetect the presence of grain in a region local to the array, eachextending from a bottom portion of the grain tank to an upper portion ofthe grain tank.
 20. The method of claim 19, wherein sensors in eacharray include at least one of optical sensors or pressure sensors.